I beat the first Medium level! Yeah!

Of course, now the second level is beating me down over and over again. The lack of laser towers and the high cost of all but the standard green towers is presenting an interesting challenge.

Incidentally, I don’t tend to completely change my tactics very often in this game. I normally settle on a rough layout within two or three goes and then the rest of my attempts are spent tweaking it, slightly changing a path, shifting the balance between upgrading existing towers versus building new towers, etc.